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Health hazard evaluation report: evaluation of indoor environmental quality in a medical office building.
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, HETA 2012-0266-3210, 2014 May; :1-17
The Health Hazard Evaluation Program received a request from employees at a medical office building. They were concerned about indoor environmental quality and exposure to sewer gas, specifically hydrogen sulfide. The medical office building was a four-story, concrete masonry office building constructed in the 1960s that had been renovated twice; the three main floors were converted into offices and exam rooms. The building was surrounded by manholes that had been identified as sources of odors. The building was within 30 feet of a 24-inch trunk line that carried sewage from approximately 60% of the surrounding area toward the wastewater treatment facility. Most of the building's current plumbing was the original cast iron waste and vent piping, which can become brittle and crack with age. We visited the facility in April 2013 and measured hydrogen sulfide, carbon dioxide, temperature, and humidity levels throughout the building. We also inspected the building's heating, ventilation, and air-conditioning system. We did not detect hydrogen sulfide in the building. We found that carbon dioxide concentrations generally increased when moving further away from the supply air discharge point on each floor; outdoor air supplied to each floor was not uniformly distributed. Temperature and humidity were within ANSI/ASHRAE recommended levels. We found problems with duct dampers, heat pumps, and the computerized control system, and determined that air flowed from the restrooms into the hallways. We found odor sources within and near the building such as dry drain traps and manholes. We recommended the employer improve the air quality in the building by (1) testing and balancing the heating, ventilation, and air-conditioning system, (2) increasing the amount of outdoor air coming into the building, and (3) fixing the problems with the duct dampers, heat pumps, and computerized control system. We also recommended the employer (1) remove plumbing fixtures and seal unused drain pipes, (2) replace cast-iron pipe with polyvinyl chloride pipe, and (3) create an employee and employer health and safety committee and hold regular meetings. We recommended employees (1) report odors to managers as soon as they occur, (2) not open building windows, and (3) participate in the health and safety committee. Following our visit, the employer reported that drain-trap devices were installed on all floor drains, HVAC components were inspected and repaired, cracks in the sanitary sewer lines were repaired, and manholes were sealed or replaced with solid lids and rain-guard devices. The employer reported that odor complaints have decreased since our evaluation.
Indoor-environmental-quality; Medical-facilities; Gases; Gas-mixtures; Gas-sampling; Odors; Office-workers; Plumbing; Sulfides; Dioxides; Temperature-measurement; Relative-humidity; Ventilation-systems; Heating-systems; Air-conditioning-equipment; Air-quality-monitoring; Air-flow; Indoor-air-pollution; Work-environment; Environmental-control-equipment; Environmental-exposure; Environmental-factors; Environmental-pollution; Engineering-controls; Administration; Exposure-assessment; Author Keywords: General Medical and Surgical Hospitals; IEQ; IAQ; indoor air; hydrogen sulfide; sewer gas; office building
Field Studies; Hazard Evaluation and Technical Assistance
NTIS Accession No.
National Institute for Occupational Safety and Health
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division